1. Field of the Invention
The present invention relates to a high-output tunnel magnetoresistive device and a low-power-consumption nonvolatile magnetic memory equipped with the same.
2. Background Art
Conventional tunnel magnetoresistive devices employ a tunnel film stack that includes an insulator film comprised of an oxide of Al (T. Miyazaki and N. Tezuka, J. Magn. Magn. Mater. 139, L231 (1995)). Because Al oxides are amorphous, they have been unable to provide sufficient electric output signals for industrial applications. Recently, it has been reported that a magnetoresistance ratio several times greater than that of the aforementioned tunnel magnetoresistive device employing an Al oxide in the insulator was obtained in a tunnel magnetoresistive device employing magnesium oxide in the insulator film (S. Yuasa. et al., Nature Material 3, 868 (2004)). Conventional nonvolatile magnetic memories are comprised of memory cells having MOSFETs on which tunnel magnetoresistive devices are formed. The MOSFETs are used for switching, and the direction of magnetization of the tunnel magnetoresistive device is rotated by means of a spatial magnetic field induced by a current upon energization of a bit line and a word line so as to write information. Readout of information is conducted based on an output voltage of the tunnel magnetoresistive device. In addition to the above magnetization rotation based on the current-induced spatial magnetic field, there is also a so-called spin-transfer torque magnetization switching, which is also known as current induced magnetization switching. In this system, a current is caused to flow directly through a magnetoresistive device so as to rotate magnetization, as disclosed in U.S. Pat. No. 5,695,864 or JP Patent Publication (Kokai) No. 2002-305337 A.
Non-patent Document 1: J. Magn. Magn. Mater. 139, L231 (1995)
Non-patent Document 2: Nature Material 3, 868 (2004)
Patent Document 1: U.S. Pat. No. 5,695,864
Patent Document 2: JP Patent Publication (Kokai) No. 2002-305337 A